Throughout the world, coffee has become one of the most popular and widely used beverages known to man. In spite of its popularity, and further in spite of the fact that the beverage has been known for several hundred years, the brewing of the beverage from the natural coffee bean is limited to two basic techniques, the drip and percolator brewing methods. As is well known in the art, the drip method of brewing coffee, which has become quite popular in recent years, is achieved by making a single pass of hot water (somewhat below the boiling point) over the coffee grounds and into a receptacle such as a glass carafe. The other method of brewing coffee from natural grounds is that of percolation and it is with such method that the present invention is concerned.
Referring now to FIG. 1, a prior art embodiment of an electric coffee percolator may be seen. Such a percolator, designated generally by the numeral 10, is operated from an AC current via a plug assembly 12 which is functional to make engagement with any standard electrical outlet. Current is passed through the plug system 12 to heating coils 14 wrapped about a heater core 16 in a case 17 received within a pump assembly 18. Application of power to the heating coil 14 is under control of a thermostat 20 which is most commonly positioned somewhere along the bottom of the percolator receptacle 10. Water passes into the confines of the pump 18 via a single orifice 22 positioned at the bottom thereof. Of course, the water entering the pump via the passageway 22 seeks its own level within the stem 24. This water encircling the heating element 14, 16 is heated to the steaming or boiling point at which time a discharge is made upward through the stem 24, forcing a head of hot water therefrom, out of the top of the stem 26, and over coffee grounds positioned within a strainer basket 28. Coffee brew then drips from the strainer basket 28 and into the water contained within the container 10. It should be understood that as water is forced up through the stem 24 and out the opening 26, a back pressure within the pump assembly 18 forces some of the fluid contained therein out through the orifice 22. More water is then drawn back in through the orifice 22 to allow the water within the stem 24 to seek its own level and the percolation cycle continues until the brew contained within the container 10 reaches a particular temperature as determined by the thermostat 20.
Certain inherent problems exist within the structure of the prior art. First, and again referring to FIG. 1, the heating chamber or pump 18 has but a single standard hole 22 provided therein, the hole providing for the ingress and egress of fluid thereinto. As noted above, when the fluid within the chamber perks up through the opening 26, a back pressure forces a certain amount of the liquid out of the hole. Since there is but a single hole 22, it has been found that much fluid remains within the heating chamber 18 on a side opposite the heating element 14, 16 from the hole 22. This coffee brew may remain in such position for a number of perk cycles without being ejected through the stem 24 or the orifice 22. The coffee bean oils contained in the liquid or brew being processed have a tendency to burn from overheating and, hence, cause the brew to become bitter or distasteful. Further, the dome-shaped cover of the heating element 18 allows sporadic emission of steam past the core 16 and upwards through the stem 24. There is no chamber provided by the confines of the pump 18 to accummulate and retain steam.
A further problem inherent with the structure of FIG. 1 is that the single orifice 22 may be in alignment with the thermostat 20 such that hot fluid is forced through the orifice 22 and onto the thermostat 20 after percolation. The coffee brew being forced out of the heating chamber is, in all likelihood, somewhat hotter than the coffee contained within the container 10 proper and hence gives a false reading to the thermostat 20 that the coffee may be near the final temperature. Also, with a single orifice 20 being provided, the cycling of brew through the heating compartment 18 and over the grounds contained within the basket 28 comes from but a single area within the container 10 and there is little agitation or mixing of the brew to minimize thermal stratification.
Further inherent problems with the prior art depicted in FIG. 1 stem from the utilization of a single heating element 14, 16 having but a single power dissipation associated therewith. If, for example, the element 14, 16 is a 600 watt element, then 600 watts of power are utilized to generate the heat necessary for not only heating the coffee to the brewing temperature but to maintain it at that temperature once the brew is completed. A problem exists in such a structure in that as the hot brew enters the orifice 22 and flows near the heating element 14, 16, a high power heater will cause the hot brew to immediately steam upon contact; the steam being dissipated up through the stem 24. As is well known to those skilled in the art, the best coffee brew is extracted from those oils within the coffee bean which are most volatile and hence the steaming coffee allows the most tasteful portion of the brew to escape. Although such a steaming effect gives a pleasant odor, it results in a diminution of coffee quality. Consequently, we have found that the utilization of but a single wattage heating element 14, 16 is undesirable.
Further, at the upper end of the brewing cycle, steam overextracts plus burns the already extracted oil.
It is a particular object of the instant invention to overcome the shortcomings in the prior art by presenting a coffee brewing device wherein the percolator pump is characterized by the presence of a plurality of evenly spaced orifices about the base thereof.
A further object of the invention is to present a coffee brewing device wherein the pump is characterized by a steam accumulator at the top thereof for accumulating steam until there is sufficient steam to cause an even cyclical surging of coffee up through the pump steam on a percolation cycle.
Yet another object of the invention is to present a coffee brewing device wherein a dual element heater assembly is utilized in conjunction with a dual thermostat configuration such that the temperature of the brew is initially raised by a high wattage heater while the final brewing cycle itself, above approximately 160.degree. F., is completed via a lower wattage heater.
Still another object of the invention is to present a beverage brewing device wherein the percolation cycle begins almost immediately upon actuation of the device, yet wherein the total brewing time is commensurate with state of the art devices, even though the brewing is completed by a lower wattage heater.
It is another object of the present invention to use uniform temperature water for percolating or pumping action in making coffee by a percolating process. It further is an object of the invention to maintain good circulation of water around the electric heater in the fountain pump to prevent any hot spots from developing in the water around the base of the heater.
Yet another object of the invention is to totally flush the water out of the pump enclosure with different pump cycles, and to heat a cylinder of water by the heater to provide a rhythmatic pumping action that is substantially equivalent to a reciprocating pumping action in the small electric heater-pump construction of the invention, and to provide a regular pumping action moving substantially all water as the pumped material.
A further object of the invention is to present a beverage brewing device which is relatively inexpensive to construct, accurate and dependable in operation, and capable of brewing coffee by percolation such that the same has a drip brewed taste quality.
These objects and other objects which will become apparent as the detailed description proceeds are achieved by apparatus for brewing coffee including a pot for receiving liquid therein; a flat-topped cylindrical member centrally positioned at the bottom of said pot, and having a plurality of uniform holes spaced about the bottom thereof providing for communication between the pot and the inside of said cylindrical member, a stem depending a short distance into said cylindrical member and extending from the top thereof for supporting a strainer thereon.
Dual element heating means are contained within a heater positioned on the bottom of the pot and supporting said member for heating water passing through the holes into the cylindrical member, said heating means being controlled by dual temperature thermostats having two preset operating temperatures. Six to ten holes are present and they have a total area of between about 0.0258 and 0.043 square inches. The flat top of the cylindrical member is spaced about 1/16" to 1/8" from a flat top on the heater.